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To:     <like.xu@linux.intel.com>
References: <20210201051039.255478-1-like.xu@linux.intel.com>
Subject: Re: [PATCH v14 00/11] KVM: x86/pmu: Guest Last Branch Recording
 Enabling
CC:     <ak@linux.intel.com>, <alex.shi@linux.alibaba.com>,
        <jmattson@google.com>, <joro@8bytes.org>, <kan.liang@intel.com>,
        <kvm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <pbonzini@redhat.com>, <seanjc@google.com>, <vkuznets@redhat.com>,
        <wanpengli@tencent.com>, <wei.w.wang@intel.com>, <x86@kernel.org>,
        "Fangyi (Eric)" <eric.fangyi@huawei.com>,
        Xiexiangyou <xiexiangyou@huawei.com>
From:   Liuxiangdong <liuxiangdong5@huawei.com>
Message-ID: <6102A1A5.90901@huawei.com>
Date:   Thu, 29 Jul 2021 20:40:05 +0800
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Hi, like.

This patch set has been merged in 5.12 kernel tree so we can use LBR in 
Guest.
Does it have requirement on CPU?
I can use lbr in guest on skylake and icelake, but cannot on IvyBridge.

I can see lbr formats(000011b) in perf_capabilities msr(0x345), but 
there is still
error when I try.

$ perf record -b
Error:
cycles: PMU Hardware doesn't support sampling/overflow-interrupts. Try 
'perf stat'

Host CPU:
Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   46 bits physical, 48 bits virtual
CPU(s):                          24
On-line CPU(s) list:             0-23
Thread(s) per core:              2
Core(s) per socket:              6
Socket(s):                       2
NUMA node(s):                    2
Vendor ID:                       GenuineIntel
CPU family:                      6
Model:                           62
Model name:                      Intel(R) Xeon(R) CPU E5-2620 v2 @ 2.10GHz
Stepping:                        4


Thanks!
Xiangdong Liu